Preparation And Gas Sensing Properties Of Electrospun Porous Nanofiber Materials

Porous materials with multi-scale porous structure,large specific surface area,high pore volume,good gas diffusion,etc are widely used in gas sensors.In this paper,PS/PLA nanoporous fiber membrane with different sizes of macropore structure and SiO₂ mesoporous nanofiber membrane with mesopore and macropore structures were designed and prepared by the facile electrospinning method.Considering the excellent optical property of porphyrin,the porous fiber membrane-supported porphyrin was used for real-time,reliable,fast and effective detection of sub-ppm to ppb level of HCl and NH₃ gas.TPPP2-PS nanoporous fiber membrane?NFM?was prepared by ''one-step"electrospinning technology based on the two mechanisms of thermally induced phase separation and non-solvent induced phase separation.The morphology,structure,thermal properties,mechanical properties and HCl gas sensitivity of TPPH₂-PS NFM were characterized by FE-SEM,CLSM,specific surface area analysis,XRD,TG,single fiber tensile strength tester and fluorescence emission spectra.Results showed that the optimum parameters were 25 w.t.%of PS,40/60?w/w?of THF/DMF,20 kV.20 cm,1.0 mL·h-1.The average fiber diameter,specific surface area,average pore size and total pore volume of TPPH₂-PS NFM were 1609 nm,58.63 m2·g-1,62.95 nm and 0.851 cm3·g-1,respectively.TPPH₂-PS NFM HCI gas sensor had obvious color change?from pink to yellow green?when exposure to HCI gas.The detection limit?DL?was found to be 46 ppb and the response time was as fast as 1s.The sensor also presented good reversibility,photostability,humidity resistance and selectivity.The eco-friendly TPPH₂-PLA and Zn?II?TPP-PLA NFMs were prepared via the same method as TPPH₂-PS NFM and the HCI and NH₃ gas senstivity was analyzed by the UV-Vis spectroscopy,respectively.The exposure to HCI gas causes a color change from pink to green of the TPPH₂-PLA NFM.The DL was found to be 34 ppb,the response time was as short as 5 s and the sensor also presented good reversibility,photostability,humidity resistance and selectivity.Zn?II?TPP-PLA NFM exhibited an excellent response/recovery performance toward sub-ppm levels of NH₃ gas.The color of the sensor changed from sandybrown to greenyellow after exposed to NH₃.The DL was found to be 0.264 ppm toward NH₃ at room temperature.In addition,the performance of the sensor was highly stable after five cycles of tracing NH₃ gas and recovery.TCPPH2-SiO₂ mesoporous nano-/micro-fiber membrane?MNM?was prepared by sol-gel-electrospinning method.The effects of the viscosity of the amino-SiO₂ sol.the electrospinning parameters and surfactant on the morphology of the fibers as well as the HCI gas senstivity of the sensor were investigated.Results showed that the optimum parameters were CTAB/F127 as the templates,1.3 Pa·S of the viscosity of the spinning sol,20 kV,20 cm,1.0 mL·h-1.The average fiber diameter,specific surface area,average pore size and total pore volume of TCPPH2-SiO₂ MNM were 320 nm,376.84 m2·g-1,3.06 nm and 0.235 cm3·g-1,respectively.TCPPH2-SiO₂ MNM had obvious color change?from mauve to green?when exposure to HCI gas.The detection limit?DL?was found to be 17 ppb and the response time was as fast as 1 s.The sensor also presented ideal reversibility and photostability.